过滤嵌套对象javascript

function filterNestedObject(obj, filterFn) {
  const result = {};
  for (let key in obj) {
    if (obj.hasOwnProperty(key)) {
      const value = obj[key];
      if (typeof value === 'object' && value !== null) {
        result[key] = filterNestedObject(value, filterFn);
      } else if (filterFn(key, value)) {
        result[key] = value;
      }
    }
  }
  return result;
}

// 使用示例
const obj = {
  name: 'John',
  age: 30,
  address: {
    city: 'New York',
    country: 'USA'
  }
};

const filteredObj = filterNestedObject(obj, (key, value) => key === 'city');
console.log(filteredObj); // { address: { city: 'New York' } }

function filterNestedObject(obj, filterFn) {
  const result = {};
  const stack = [{ obj, key: null }];

  while (stack.length > 0) {
    const { obj, key } = stack.pop();
    for (let prop in obj) {
      if (obj.hasOwnProperty(prop)) {
        const value = obj[prop];
        const nestedKey = key ? `${key}.${prop}` : prop;
        if (typeof value === 'object' && value !== null) {
          stack.push({ obj: value, key: nestedKey });
        } else if (filterFn(nestedKey, value)) {
          result[nestedKey] = value;
        }
      }
    }
  }

  return result;
}

// 使用示例
const obj = {
  name: 'John',
  age: 30,
  address: {
    city: 'New York',
    country: 'USA'
  }
};

const filteredObj = filterNestedObject(obj, (key, value) => key === 'address.city');
console.log(filteredObj); // { 'address.city': 'New York' }